The problem of avoiding or minimizing power disturbances and interruptions to computer circuits and similar critical loads is not new. Several arrangements have, in the past, been proposed, including the use of surge arrestors, filters, isolating transformers, regulators, motor-generator sets and uninterrupted power supply systems. Such usage in the prior art has been found extremely expensive, and not always entirely satisfactory. Representative of the prior art are the below listed U.S. Pat. Nos.: 1,985,639 King, Jr., 2,922,896 Ohlund, 3,337,742 Baehr et al., 3,959,778 Brette.